In general, the axle assembly for the steerable wheels of a floor-type industrial vehicle, such as a fork-lift truck, must permit a high degree of angular displacement of each of the steerable wheels to provide for the necessary maneuverability of the vehicle into close spaces and with a minimum of turning room.
Fork-lift trucks have thus been provided with axle assemblies which comprise an elongated axle body upon which the steerable wheels are pivotally mounted at the ends of this body and a tie bar which connects these wheels with a steering knuckle swingably mounted upon the body intermediate these ends. In addition, it is a common practice to provide a hydraulic cylinder which is coupled with the steering linkage to actuate the latter.
In conventional steering-axle assemblies of this type, the tie bars are generally disposed above or below the axle body, usually the latter, and the hydraulic cylinder is likewise disposed outside the axle body.
The hydraulic cylinder is either swingably mounted upon the axle body or on the vehicle frame or chassis to which the axle body is secured. This latter arrangement has the disadvantage that the steering forces are transferred from the vehicle frame and the fastening elements to the axle body.
When the steering knuckle and/or the tie bar or tie bars or the hydraulic cylinder are disposed outside of the axle body, these elements can be subjected to impact and have tendency to bend, thereby damaging the steering linkage or interferring therewith. The elements of the steering linkage thus are exposed to external effects and can be nicked, bent or otherwise affected.
All of these have proved to be disadvantageous in such industrial or floor vehicles as fork-lift trucks and have been found to be most detrimental when the steering linkage must impart a small turning radius to the vehicle.